title: The saccus vasculosus of fish is a sensor of seasonal changes in day length.
abstract: The pars tuberalis of the pituitary gland is the regulatory hub for seasonal reproduction in birds and mammals. Although fish also exhibit robust seasonal responses, they do not possess an anatomically distinct pars tuberalis. Here we report that the saccus vasculosus of fish is a seasonal sensor. We observe expression of key genes regulating seasonal reproduction and rhodopsin family genes in the saccus vasculosus of masu salmon. Immunohistochemical studies demonstrate that all of these genes are expressed in the coronet cells of the saccus vasculosus, suggesting the existence of a photoperiodic signalling pathway from light input to neuroendocrine output. In addition, isolated saccus vasculosus has the capacity to respond to photoperiodic signals, and its removal abolishes photoperiodic response of the gonad. Although the physiological role of the saccus vasculosus has been a mystery for several centuries, our findings indicate that the saccus vasculosus acts as a sensor of seasonal changes in day length in fish.
authors.affiliation: Laboratory of Animal Physiology, Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nakane
authors.forename: Keisuke
authors.initials: K
authors.lastname: Ikegami
authors.forename: Masayuki
authors.initials: M
authors.lastname: Iigo
authors.forename: Hiroko
authors.initials: H
authors.lastname: Ono
authors.forename: Korenori
authors.initials: K
authors.lastname: Takeda
authors.forename: Daisuke
authors.initials: D
authors.lastname: Takahashi
authors.forename: Maiko
authors.initials: M
authors.lastname: Uesaka
authors.forename: Meita
authors.initials: M
authors.lastname: Kimijima
authors.forename: Ramu
authors.initials: R
authors.lastname: Hashimoto
authors.forename: Natsumi
authors.initials: N
authors.lastname: Arai
authors.forename: Takuya
authors.initials: T
authors.lastname: Suga
authors.forename: Katsuya
authors.initials: K
authors.lastname: Kosuge
authors.forename: Tomotaka
authors.initials: T
authors.lastname: Abe
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Maeda
authors.forename: Takumi
authors.initials: T
authors.lastname: Senga
authors.forename: Noriko
authors.initials: N
authors.lastname: Amiya
authors.forename: Teruo
authors.initials: T
authors.lastname: Azuma
authors.forename: Masafumi
authors.initials: M
authors.lastname: Amano
authors.forename: Hideki
authors.initials: H
authors.lastname: Abe
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Yamamoto
authors.forename: Takashi
authors.initials: T
authors.lastname: Yoshimura
mesh_terms: D000825:Animal Structures / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D000818:Animals; D001345:Autoradiography; D001921:Brain / Q000378:metabolism; D002478:Cells, Cultured; D005399:Fishes / Q000033:anatomy & histology* / Q000235:genetics / Q000502:physiology*; D005786:Gene Expression Regulation; D008297:Male; D005810:Multigene Family; D017440:Photoperiod; D012098:Reproduction / Q000235:genetics; D012243:Rhodopsin / Q000235:genetics / Q000378:metabolism; D012621:Seasons; D015398:Signal Transduction / Q000235:genetics; D013737:Testis / Q000254:growth & development / Q000378:metabolism
chemical_list: D012243:Rhodopsin